Activate Function from child class Flutter-CodePudding

So I want to trigger a function out of a child class in flutter. This is the part where the function should be triggered

onTap: onItemTap,

I tried passing the function on like this:

Parent:

bottomNavigationBar: BottomBar(onItemTap(_selectedIndex))

Function in parent:

  void _onItemTap(int index) {
    setState(() {
      _selectedIndex = index;
    });
  }

Child:

  final void Function(int _selectedIndex) onItemTap;
  const BottomBar( this.onItemTap);

But I get this error in my Parent:

This expression has a type of 'void' so its value can't be used

How do I pass the function on properly?

CodePudding user response：

You can use _onItemTap as a tear-off directly, just do:

bottomNavigationBar: BottomBar(_onItemTap)

The BottomBar expects a void Function(int _selectedIndex) which literally means A void function that takes one parameter that is an int since _onItemTap is exactly that, it can be passed directly.